Feat rule webpack entry point

src/rules/eslint-types.js

@@ -0,0 +1,16 @@
+module.exports = {
+	types: {
+		ArrayExpression: 'ArrayExpression',
+		ArrowFunctionExpression: 'ArrowFunctionExpression',
+		AssignmentExpression: 'AssignmentExpression',
+		BlockStatement: 'BlockStatement',
+		CallExpression: 'CallExpression',
+		ExpressionStatement: 'ExpressionStatement',
+		FunctionExpression: 'FunctionExpression',
+		Identifier: 'Identifier',
+		MemberExpression: 'MemberExpression',
+		ObjectExpression: 'ObjectExpression',
+		Property: 'Property',
+		ReturnStatement: 'ReturnStatement',
+	},
+};

src/rules/webpack-entry-point.js

@@ -0,0 +1,227 @@
+const path = require('path');
+const { types } = require('./eslint-types');
+/*
+  Ensure that the `webpack.config.js` file correctly specifies the entry point
+  as `aurelia-bootstrapper`.
+
+  It expects the export to look something like this (exporting either a function or object)
+
+   module.exports = function () {
+     return {
+       entry: {
+         app: ['aurelia-bootstrapper']
+       },
+     }
+   };
+*/
+
+const webpackConfigFileName = 'webpack.config.js';
+
+const isAssignedToModuleExports = context => {
+	const ancestors = context.getAncestors();
+
+	const appProperty = ancestors.pop();
+	if (
+		!appProperty ||
+		appProperty.type !== types.Property ||
+		appProperty.key.name !== 'app'
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring appProperty', appProperty);
+
+		return false;
+	}
+
+	const entryObjectExpression = ancestors.pop();
+	if (
+		!entryObjectExpression ||
+		entryObjectExpression.type !== types.ObjectExpression
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring entryObjectExpression', entryObjectExpression);
+		return false;
+	}
+
+	const entryProperty = ancestors.pop();
+	if (
+		!entryProperty ||
+		entryProperty.type !== types.Property ||
+		entryProperty.key.name !== 'entry'
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring entryProperty', entryProperty);
+		return false;
+	}
+
+	const objectExpression = ancestors.pop();
+	if (!objectExpression || objectExpression.type !== types.ObjectExpression) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring objectExpression', objectExpression);
+		return false;
+	}
+
+	// TODO Handle direct assignment rather than functions
+	// TODO Handle arrow functions with body
+	const returnStatementOrArrowFunctionExpression = ancestors.pop();
+	if (!returnStatementOrArrowFunctionExpression) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log(
+			'Ignoring returnStatementOrArrowFunctionExpression',
+			returnStatementOrArrowFunctionExpression
+		);
+		return false;
+	}
+
+	if (returnStatementOrArrowFunctionExpression.type === types.ReturnStatement) {
+		const blockStatement = ancestors.pop();
+		if (!blockStatement || blockStatement.type !== types.BlockStatement) {
+			// TODO: Remove Console
+			// eslint-disable-next-line no-console
+			console.log('Ignoring blockStatement', blockStatement);
+			return false;
+		}
+
+		const functionExpression = ancestors.pop();
+		if (
+			!functionExpression ||
+			functionExpression.type !== types.FunctionExpression
+		) {
+			// TODO: Remove Console
+			// eslint-disable-next-line no-console
+			console.log('Ignoring functionExpression', functionExpression);
+			return false;
+		}
+	} else if (
+		returnStatementOrArrowFunctionExpression.type ===
+		types.ArrowFunctionExpression
+	) {
+		// No additional tokens to consume
+	} else {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log(
+			'Ignoring unknown type returnStatementOrArrowFunctionExpression',
+			returnStatementOrArrowFunctionExpression
+		);
+	}
+
+	const assignmentExpression = ancestors.pop();
+	if (
+		!assignmentExpression ||
+		assignmentExpression.type !== types.AssignmentExpression ||
+		assignmentExpression.operator !== '='
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring assignmentExpression', assignmentExpression);
+		return false;
+	}
+
+	const expressionStatement = ancestors.pop();
+	if (
+		!expressionStatement ||
+		expressionStatement.type !== types.ExpressionStatement
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring expressionStatement', expressionStatement);
+		return false;
+	}
+
+	const leftHandSideOfExpressionStatement = expressionStatement.expression.left;
+	if (
+		!leftHandSideOfExpressionStatement ||
+		leftHandSideOfExpressionStatement.type !== types.MemberExpression
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log(
+			'Ignoring leftHandSideOfExpressionStatement',
+			leftHandSideOfExpressionStatement
+		);
+		return false;
+	}
+
+	const object = leftHandSideOfExpressionStatement.object;
+	if (!object || object.type !== types.Identifier || object.name !== 'module') {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring object', object);
+		return false;
+	}
+
+	const property = leftHandSideOfExpressionStatement.property;
+	if (
+		!property ||
+		property.type !== types.Identifier ||
+		property.name !== 'exports'
+	) {
+		// TODO: Remove Console
+		// eslint-disable-next-line no-console
+		console.log('Ignoring property', property);
+		return false;
+	}
+
+	return true;
+};
+
+const webpackEntryPointIsAureliaBootrap = context => node => {
+	const basename = path.basename(context.getFilename());
+
+	// Only webpack.config.js is checked
+	if (basename !== webpackConfigFileName) {
+		return;
+	}
+
+	if (node.name === 'app') {
+		if (!isAssignedToModuleExports(context)) {
+			return;
+		}
+
+		const parent = node.parent;
+		const value = parent.value;
+		if (value.type !== types.ArrayExpression) {
+			context.report({
+				node,
+				message: 'entry.app must be an array of strings',
+			});
+			return;
+		}
+		const elements = value.elements;
+
+		if (elements.length !== 1 || elements[0].value !== 'aurelia-bootstrapper') {
+			context.report({
+				node,
+				message:
+					"entry.app must be ['aurelia-bootstrapper']: found {{ value }}",
+				data: {
+					value: context.getSourceCode().getText(value),
+				},
+			});
+			return;
+		}
+	}
+};
+
+module.exports = {
+	meta: {
+		type: 'problem',
+		docs: {
+			description: 'TODO',
+			category: 'aurelia',
+			fixable: 'code',
+		},
+	},
+	create: context => {
+		// state here
+
+		return {
+			Identifier: webpackEntryPointIsAureliaBootrap(context),
+		};
+	},
+};

test/rules/webpack-entry-point.spec.js

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+import eslint from 'eslint';
+import rule from '../../src/rules/webpack-entry-point';
+
+const ruleTester = new eslint.RuleTester({ parser: 'babel-eslint' });
+
+const moduleExportsAsFunction = ({ app }) => `
+  module.exports = function () {
+    return {
+      entry: {
+        ${app ? `app: ['${app}']` : ''}
+      },
+    }
+  };
+`;
+
+const moduleExportsAsArrowFunction = ({ app }) => `
+  module.exports = ({ production, server, extractCss, coverage, analyze, karma } = {}) => ({
+    entry: {
+      ${app ? `app: ['${app}']` : ''}
+    },
+  });
+`;
+
+const embedFilenameInCode = ({ filename, code }) => ({
+	filename,
+	code: `// filename=${filename}\n${code}`,
+});
+
+// Use https://astexplorer.net/ and `espree` tokens to transform your `code`
+// into an AST for use here.
+ruleTester.run('webpack-entry-point', rule, {
+	valid: [
+		{
+			// Only webpack.config.js is checked for valid entry.app values
+			...embedFilenameInCode({
+				filename: '/some/dir/not.webpack.config.js',
+				code: moduleExportsAsFunction({ app: 'not-aurelia-bootstrapper' }),
+			}),
+		},
+		{
+			...embedFilenameInCode({
+				filename: '/some/dir/webpack.config.js',
+				code: moduleExportsAsArrowFunction({ app: 'aurelia-bootstrapper' }),
+			}),
+		},
+	],
+	invalid: [
+		{
+			...embedFilenameInCode({
+				filename: '/some/dir/webpack.config.js',
+				code: moduleExportsAsFunction({ app: 'not-aurelia-bootstrapper' }),
+			}),
+			errors: [
+				{
+					message:
+						"entry.app must be ['aurelia-bootstrapper']: found ['not-aurelia-bootstrapper']",
+					type: 'Identifier',
+				},
+			],
+		},
+		{
+			...embedFilenameInCode({
+				filename: '/some/dir/webpack.config.js',
+				code: moduleExportsAsArrowFunction({ app: 'not-aurelia-bootstrapper' }),
+			}),
+			errors: [
+				{
+					message:
+						"entry.app must be ['aurelia-bootstrapper']: found ['not-aurelia-bootstrapper']",
+					type: 'Identifier',
+				},
+			],
+		},
+	],
+});